Superabsorbent polymer and method for producing same

Abstract

The present disclosure relates to a superabsorbent polymer and a method for preparing the same. More specifically, provided are: a superabsorbent polymer capable of exhibiting improved bacterial growth inhibition characteristics without degrading absorption performance; and a method for preparing the same.

Description

[0001] This application is a divisional application of the Chinese patent application with the application date of March 17, 2022, application number "202280004743.9", and invention name "Superabsorbent polymer and preparation method thereof". Technical Field

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of Korean Patent Application No. 10-2021-0036095 filed in the Korean Intellectual Property Office on March 19, 2021, and Korean Patent Application No. 10-2022-0032857 filed in the Korean Intellectual Property Office on March 16, 2022, the disclosures of which are incorporated herein by reference in their entirety.

[0004] The present disclosure relates to superabsorbent polymers capable of exhibiting improved bacterial growth inhibition properties without sacrificing absorbency and methods of making the same. Background Art

[0005] Super absorbent polymer (SAP) is a synthetic polymer material that can absorb 500 to 1000 times its own weight in water. Manufacturers call it different names, such as SAM (Super Absorbency Material), AGM (Absorbent Gel Material), etc. Such super absorbent polymers have begun to be used in sanitary products, and they are now widely used not only in sanitary products such as disposable diapers for children, but also in water-retaining soil products for gardening, water-stopping materials for civil engineering and construction, sheets for seedling cultivation, preservatives for food circulation, materials for poultices, or in the field of electrical insulation.

[0006] In particular, such superabsorbent polymers are most widely used in sanitary products or disposable absorbent products such as disposable diapers for children or adults. Therefore, when bacteria proliferate in these sanitary products and disposable absorbent products, various diseases are induced and even secondary odors may be caused, which is a problem. Therefore, attempts have been made to introduce various bacteria growth inhibitory components, deodorizing components, or antibacterial components into superabsorbent polymers.

[0007] However, in attempts to introduce bacteria growth inhibiting antimicrobial agents into super absorbent polymers, it is not easy to select and introduce antimicrobial agents that exhibit excellent bacteria growth inhibiting properties and deodorizing properties while being harmless to the human body, satisfying economic benefits, and not deteriorating the basic physical properties of super absorbent polymers.

[0008] Therefore, there is a continuing need to develop superabsorbent polymer-related technologies that can exhibit excellent bacterial growth inhibition properties without degrading the basic physical properties of the superabsorbent polymer. Summary of the invention

[0009] Technical issues

[0010] Therefore, a superabsorbent polymer capable of exhibiting improved bacterial growth inhibition characteristics without reducing absorption performance and a method for preparing the same are provided.

[0011] Technical Solution

[0012] According to one embodiment of the present disclosure,

[0013] A superabsorbent polymer is provided, comprising:

[0014] an acrylic acid-based monomer, a polymerizable antibacterial monomer represented by the following Chemical Formula 1, and a polymer of an internal crosslinking agent, wherein the acrylic acid-based monomer contains an acidic group, wherein at least a portion of the acidic group is neutralized,

[0015] Wherein the polymerizable antibacterial monomer is contained in the polymer in an amount of 0.2 parts by weight to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer:

[0016] [Chemical formula 1]

[0017]

[0018] In Chemical Formula 1,

[0019] R 1 To R 3 are each independently hydrogen or methyl, and

[0020] A is a substituted or unsubstituted C6 to C60 aromatic ring.

[0021] According to another embodiment of the present disclosure,

[0022] A method for preparing a superabsorbent polymer is provided, the method comprising the following steps:

[0023] preparing a monomer composition by mixing an acrylic acid-based monomer containing an acidic group, a polymerizable antibacterial monomer represented by Chemical Formula 1, a basic substance, an internal cross-linking agent, and a polymerization initiator;

[0024] forming a hydrogel polymer by thermally or photopolymerizing the monomer composition; and

[0025] The super absorbent polymer comprising the polymer is formed by drying, pulverizing and classifying the hydrogel polymer,

[0026] The polymerizable antibacterial monomer is used in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer.

[0027] Furthermore, according to another embodiment of the present disclosure, provided is a sanitary product including the superabsorbent polymer.

[0028] Beneficial Effects

[0029] The superabsorbent polymer of the present disclosure may exhibit antimicrobial activity capable of inhibiting the growth of bacteria that are harmful to the human body and may cause secondary odors.

[0030] Specifically, since the super absorbent polymer is prepared by using a polymerizable antibacterial monomer having a specific structure when forming the polymer, it exhibits antibacterial activity against at least one of Gram-positive bacteria and Gram-negative bacteria. In addition, unlike polymers using other antibacterial agents, it can maintain excellent water retention capacity, and the antibacterial monomer used does not remain in the polymer, so there is no stability problem in the human body caused by the outflow of the antibacterial agent.

[0031] Therefore, the superabsorbent polymer can be very preferably applied to various sanitary products requiring antibacterial activity against bacteria such as diapers for children and diapers for adults. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The polymerizable antibacterial monomer 1-1 1 H NMR spectrum. DETAILED DESCRIPTION

[0033] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the present invention. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. It should also be understood that the terms "including", "having" or "having" when used in this specification indicate the presence of the features, steps, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, steps, components, or combinations thereof.

[0034] Furthermore, as used herein, when it is mentioned that a layer or an element is formed “on” a layer or an element, the layer or element may be directly formed on the layer or element, or other layers or elements may be additionally formed between layers, on an object, or on a substrate.

[0035] Since the present invention can be modified in various ways and has various forms, its specific embodiments are shown by way of example and will be described in detail. However, this is not intended to limit the present invention to the specific forms disclosed, and it should be understood that the present invention includes all modifications, equivalents and alternatives within the concept and technical scope of the present invention.

[0036] Furthermore, the terms are used only to refer to specific embodiments and are not intended to limit the present disclosure. Unless the context indicates differently, a singular expression of the present disclosure may include a plural expression.

[0037] Meanwhile, the term "(meth)acrylate" used herein includes both acrylate and methacrylate.

[0038] In the present disclosure, the alkyl group may be linear or branched, and the carbon number thereof is not particularly limited, but is preferably 1 to 20. According to one embodiment, the carbon number of the alkyl group is 1 to 10. According to another embodiment, the carbon number of the alkyl group is 1 to 6. Specific examples of the alkyl group include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methyl-butyl, 1-ethyl-butyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, n-heptyl, 1-methylhexyl, cyclopentylmethyl, cyclohexylmethyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethyl-propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl and the like, but are not limited thereto. Furthermore, in the present disclosure, the above description of the alkyl group may be applied to the alkylene group, except that the alkylene group is a divalent group.

[0039] The term "polymer" in the present disclosure is in a state in which an acrylic acid-based monomer is polymerized, and may include all water content ranges or all particle size ranges. Among polymers, a polymer having a water content of about 40% by weight or more after polymerization and before drying may be referred to as a hydrogel polymer, and particles in which a hydrogel polymer is pulverized and dried may be referred to as a cross-linked polymer.

[0040] Furthermore, the term "superabsorbent polymer particles" refers to a granular material including a cross-linked polymer in which an acrylic acid-based monomer having an acidic group that is at least partially neutralized is polymerized and cross-linked by an internal cross-linking agent.

[0041] Furthermore, depending on the context, the term "superabsorbent polymer" is used to encompass all of the following: a polymer in which acrylic acid-based monomers having at least partially neutralized acidic groups are polymerized or a base resin in the form of a powder consisting of superabsorbent polymer particles in which the polymer is crushed, as well as the polymer or the base resin that has been further processed (e.g., surface cross-linking, fine powder reassembly, drying, crushing, classification, etc.) to be in a state suitable for commercialization.

[0042] In order to ensure antibacterial properties and deodorizing properties in conventional super absorbent polymers, metal compounds having antibacterial functions or organic compounds containing cations or alcohol functional groups are introduced as additives. However, in this case, the safety of the super absorbent polymer is deteriorated or basic physical properties such as absorption properties are reduced, and there are problems in the durability of antibacterial activity and leakage of antibacterial substances.

[0043] As an example, attempts have been made to introduce antimicrobial components containing antimicrobial metal ions such as silver, copper, copper or zinc into superabsorbent polymers. These components containing antimicrobial metal ions destroy the cell walls of microorganisms such as bacteria, and kill bacteria with enzymes that may cause odors in superabsorbent polymers, thereby imparting deodorizing properties. However, components containing metal ions are classified as biocides (BIOCIDE) materials that can kill even microorganisms that are beneficial to the human body. For this reason, when superabsorbent polymers are applied to sanitary products such as diapers for children or adults, the introduction of antimicrobial components containing metal ions is excluded as much as possible.

[0044] In addition, when a bacteria growth inhibiting antimicrobial agent is introduced into a superabsorbent polymer, a method of blending a small amount of the antimicrobial agent with the superabsorbent polymer is mainly applied. However, when this blending method is applied, it is actually difficult to uniformly maintain the bacteria growth inhibiting property over time. In addition, during the process of blending the superabsorbent polymer with the antimicrobial agent, such a blending method may cause uneven coating and desorption of the antimicrobial agent component, and there are also disadvantages such as the need to install new equipment for blending.

[0045] In addition, there are various types of bacteria, of which more than 5,000 species have been identified. Specifically, bacteria have various cell shapes such as spherical, rod-shaped, spiral, etc., and the degree of aerobicity of various bacteria is also different, so that bacteria are classified into aerobic bacteria, facultative bacteria, and anaerobic bacteria. Therefore, one type of antibacterial agent does not easily have a physical / chemical mechanism that can destroy the cell membrane / cell wall of various bacteria or denature proteins.

[0046] However, it was determined that a super absorbent polymer prepared by polymerizing a carboxyl-containing monomer having a specific structure together with an acrylic acid-based monomer can exhibit antibacterial activity against at least one of Gram-positive bacteria and Gram-negative bacteria while exhibiting absorption performance above a certain level, thereby completing the present invention.

[0047] More specifically, when the polymerizable antibacterial monomer represented by Chemical Formula 1 comes into contact with bacteria, an acidic condition is formed by the dissociation of the carboxyl group (COOH) substituted in Ring A. Under acidic conditions, bacteria are affected by the cell membrane structure and function, and thus the growth of bacteria can be reduced. Therefore, the superabsorbent polymer including the polymer formed by the polymerizable antibacterial monomer represented by Chemical Formula 1 can exhibit antibacterial activity against at least one of Gram-positive bacteria and Gram-negative bacteria.

[0048] In addition, since the super absorbent polymer contains the antibacterial monomer in the form of a cross-linked polymer together with the acrylic acid-based monomer, the antibacterial monomer does not remain in the super absorbent polymer in the form of a compound. Therefore, even with the passage of time, there is no problem of the antibacterial agent flowing out, and thus the super absorbent polymer exhibits excellent stability.

[0049] Hereinafter, a super absorbent polymer and a preparation method thereof according to specific embodiments of the present invention will be described in more detail.

[0050] Superabsorbent polymer

[0051] Specifically, the superabsorbent polymer according to one embodiment of the present disclosure comprises a polymer of an acrylic acid-based monomer, a polymerizable antibacterial monomer, and an internal crosslinking agent, wherein the acrylic acid-based monomer contains an acidic group, wherein at least a portion of the acidic group is neutralized,

[0052] The polymerizable antibacterial monomer is represented by the following Chemical Formula 1, at least some of the carboxyl groups (COOH) in the following Chemical Formula 1 are neutralized, and the polymerizable antibacterial monomer is included in the polymer in an amount of 0.2 parts by weight to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer:

[0053] [Chemical formula 1]

[0054]

[0055] In Chemical Formula 1,

[0056] R 1 To R 3 are each independently hydrogen or methyl, and

[0057] A is a substituted or unsubstituted C6 to C60 aromatic ring.

[0058] Herein, the polymer is obtained by cross-linking and polymerizing an acrylic acid-based monomer and a polymerizable antibacterial monomer in the presence of an internal cross-linking agent, and may have a three-dimensional network structure in which the main chain formed by polymerizing the above monomers is cross-linked by the internal cross-linking agent. Therefore, the polymerizable antibacterial monomer does not exist as a separate compound in the superabsorbent polymer, but exists as a repeating unit constituting the main chain, so that it does not leak over time. Therefore, the antibacterial activity of the superabsorbent polymer can be continuously maintained.

[0059] In addition, in the present disclosure, the polymerizable antibacterial monomer may be understood to include all of the carboxylic acid compound represented by Chemical Formula 1 and the carboxylate anion-containing compound represented by Chemical Formula 1' in which the carboxylic acid compound represented by Chemical Formula 1 is neutralized by an alkaline substance. In other words, the polymerizable monomer has a structure in which at least some of the carboxyl groups (COOH) in Chemical Formula 1 are neutralized.

[0060] [Chemical Formula 1']

[0061]

[0062] In Chemical Formula 1',

[0063] The description of each substituent is as defined in Chemical Formula 1.

[0064] Therefore, the polymer contained in the superabsorbent polymer includes: an acidic group of an acrylic acid-based monomer, a substituent in which the acidic group of the acrylic acid-based monomer is neutralized by an alkaline substance, a carboxyl group of a polymerizable antibacterial monomer represented by Chemical Formula 1, and a substituent in which the carboxyl group of the polymerizable antibacterial monomer is neutralized. Specifically, the polymer includes all of the following: a carboxyl group (COOH) of an acrylic acid monomer, a carboxylate group (COO-) in which the carboxyl group is neutralized, a carboxyl group (COOH) of a polymerizable antibacterial monomer, and a carboxylate group (COO-) in which the carboxyl group is neutralized. In this case, the anionic carboxylate group (COO-) can be bonded to the cationic ion of the alkaline substance used for neutralization.

[0065] In this article, as the alkaline substance that can neutralize the monomer based on acrylic acid and polymerizable antibacterial monomer, the alkaline substance such as sodium hydroxide, potassium hydroxide and ammonium hydroxide can be used.At this moment, based on the total mole number of the monomer based on acrylic acid for preparing polymer, the neutralization degree of the monomer based on acrylic acid, that is, the content (mol%) of the monomer based on acrylic acid that is neutralized can be 40mol% to 95mol%, 40mol% to 80mol% or 45mol% to 75mol%.In addition, based on the total mole number of the polymerizable antibacterial monomer for preparing polymer, the neutralization degree of the polymerizable antibacterial monomer, that is, the content (mol%) of the polymerizable antibacterial monomer that is neutralized can be 40mol% to 95mol%, 40mol% to 80mol% or 45mol% to 75mol%.Excessively high neutralization degree causes the precipitation of the neutralized monomer, and therefore may not be easy to polymerize.On the contrary, too low neutralization degree not only deteriorates the absorbency of polymer, but also gives polymer difficult to handle characteristics, such as the characteristics of elastic rubber.

[0066] Therefore, the polymer of the super absorbent polymer contains, in addition to the repeating unit derived from the acrylic acid-based monomer, a repeating unit derived from a polymerizable antimicrobial monomer having a carboxyl group (COOH) and a carboxylate group (COO-) in which the carboxyl group is neutralized. Therefore, even if the polymerizable antimicrobial monomer is added, the absorption performance of the super absorbent polymer does not decrease, and even with the lapse of time, the antimicrobial activity does not deteriorate because leakage of the antimicrobial monomer is prevented.

[0067] In addition, based on 100 parts by weight of acrylic acid-based monomers, the polymerizable antibacterial monomer is included in the polymer in an amount of 0.2 to 20 parts by weight. When the polymerizable antibacterial monomer is included in an amount of less than 0.2 parts by weight based on 100 parts by weight of acrylic acid-based monomers, it is difficult to show sufficient antibacterial activity. When the polymerizable antibacterial monomer is included in an amount greater than 20 parts by weight based on 100 parts by weight of acrylic acid-based monomers, the absorption performance of the superabsorbent polymer may deteriorate. Specifically, based on 100 parts by weight of acrylic acid-based monomers, a superabsorbent polymer containing more than 20 parts by weight of a polymerizable antibacterial monomer in a polymer exhibits a centrifuge retention capacity (CRC) of less than 31g / g, thereby having a poor liquid retention capacity. Therefore, it is not suitable for use in sanitary products.

[0068] More specifically, the polymerizable antibacterial monomer may be contained in the polymer in an amount of 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, or 0.5 parts by weight or more, and 20 parts by weight or less, 18 parts by weight or less, 15 parts by weight or less, 13 parts by weight or less, 10 parts by weight or less, 8 parts by weight or less, 5 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, or 2 parts by weight or less, based on 100 parts by weight of the acrylic acid-based monomer. Herein, in terms of maintaining the absorption properties of the superabsorbent polymer such as centrifugal retention capacity, the polymerizable antibacterial monomer is preferably contained in an amount of 0.5 to 2 parts by weight, based on 100 parts by weight of the acrylic acid-based monomer.

[0069] At this time, "the polymerizable antibacterial monomer is contained in the polymer in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer" means that when preparing the polymer, the polymerizable antibacterial monomer is added in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer. This can be determined by whether the antibacterial monomer is detected when checking the residual monomers of the superabsorbent polymer. Since the antibacterial monomer is not detected in the superabsorbent polymer after preparation, it can be seen that the entire amount of the antibacterial monomer used is used for polymerization with the acrylic acid-based monomer.

[0070] In addition, in Chemical Formula 1, A may be a C6 to C60 aromatic ring which is unsubstituted or substituted with at least one substituent selected from the group consisting of a C1 to C4 alkyl group, a hydroxyl group, and a carboxyl group.

[0071] In one embodiment, A may be a C6 to C10 aromatic ring which is unsubstituted or substituted with at least one substituent selected from the group consisting of a C1 to C4 alkyl group, a hydroxyl group, and a carboxyl group.

[0072] Specifically, A may be a benzene ring which is unsubstituted or substituted with at least one substituent (eg, one to five substituents) selected from a C1 to C4 alkyl group, a hydroxyl group, and a carboxyl group.

[0073] For example, the polymerizable antibacterial monomer may be any one selected from the following:

[0074]

[0075] Meanwhile, the acrylic acid-based monomer is a compound represented by the following Chemical Formula 2:

[0076] [Chemical formula 2]

[0077] R-COOM'

[0078] In chemical formula 2,

[0079] R is a C2 to C5 hydrocarbon group having an unsaturated bond, and

[0080] M' is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.

[0081] Preferably, the monomer may be at least one selected from (meth)acrylic acid and its monovalent (alkali) metal salt, divalent metal salt, ammonium salt and organic amine salt.

[0082] Therefore, when (meth)acrylic acid and / or a salt thereof is used as the acrylic acid-based monomer, a super absorbent polymer having improved absorption properties can be obtained, which is preferred.

[0083] In addition, the term "internal crosslinking agent" used herein is different from the surface crosslinking agent used to crosslink the surface of the super absorbent polymer particles to be described later, and the internal crosslinking agent polymerizes the unsaturated bonds of the acrylic acid-based monomer and the polymerizable antibacterial monomer by crosslinking. The crosslinking in the above steps is performed both on the surface and inside, but when the surface crosslinking process of the super absorbent polymer particles to be described later is performed, the surface of the particles of the super absorbent polymer finally prepared has a structure crosslinked by the surface crosslinking agent, and the inside of the particles has a structure crosslinked by the internal crosslinking agent.

[0084] As the internal crosslinking agent, any compound may be used as long as it allows the introduction of a crosslinking bond during the polymerization of the acrylic acid-based monomer. As a non-limiting example, the internal crosslinking agent may be a multifunctional crosslinking agent. Specifically, it can be N, N'-methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol (meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol (meth)acrylate, butanediol di(meth)acrylate, butanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipentaerythritol pentaacrylate, glycerol tri(meth)acrylate, pentaerythritol tetraacrylate, triarylamine, ethylene glycol diglycidyl ether, propylene glycol, glycerol, or ethylene carbonate, and these can be used alone or in combination of two or more. However, the present disclosure is not limited thereto.

[0085] Preferably, the internal cross-linking agent may be a polyalkylene glycol di(meth)acrylate-based compound, such as polyethylene glycol (meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, or polypropylene glycol (meth)acrylate.

[0086] The cross-linking polymerization of the acrylic acid-based monomer in the presence of an internal cross-linking agent can be performed by thermal polymerization, photopolymerization or mixed polymerization in the presence of a polymerization initiator with or without a thickener, a plasticizer, a storage stabilizer, an antioxidant, etc., but the specific details will be described later.

[0087] In addition, superabsorbent polymer can be in the form of particles with a particle size of 850 μm or less, for example, about 150 μm to 850 μm. At this time, the particle size can be measured according to EDANA (European Disposables and Nonwovens Association, European Disposables and Nonwoven Fabrics Association) WSP 220.3. When superabsorbent polymer includes a large amount of fine powders with a particle size less than 150 μm, various physical properties of superabsorbent polymer may deteriorate, which is not preferred.

[0088] At the same time, the superabsorbent polymer may also include a surface crosslinked layer formed by further crosslinking the polymer using a surface crosslinking agent on the polymer. This is to increase the surface crosslinking density of the superabsorbent polymer particles. As described above, when the superabsorbent polymer particles also include a surface crosslinked layer, they have a structure with a higher crosslinking density on the outside than on the inside.

[0089] As the surface crosslinking agent, any surface crosslinking agent conventionally used in the preparation of super absorbent polymers may be used without any particular limitation. Examples of the surface crosslinking agent may include: at least one polyol selected from ethylene glycol, propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexanediol, 1,2-hexanediol, 1,3-hexanediol, 2-methyl-1,3-propylene glycol, 2,5-hexanediol, 2-methyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, tripropylene glycol and glycerol; at least one carbonate-based compound selected from ethylene carbonate, propylene carbonate and glycerol carbonate; an epoxy compound such as ethylene glycol diglycidyl ether; Azoline compounds, e.g. Oxazolidinone; Polyamine compound; Oxazoline compounds; Mono Oxazolidinone, di Oxazolidinone or polyoxazolidinone Oxazolidinone compounds; cyclic urea compounds; and the like.

[0090] Specifically, one or more, two or more, or three or more of the above-mentioned surface crosslinking agents may be used as the surface crosslinking agent, for example, ethylene carbonate-propylene carbonate (ECPC), propylene glycol and / or glycerol carbonate may be used.

[0091] At the same time, as described above, the superabsorbent polymer may exhibit antimicrobial activity against at least one of gram-negative bacteria and gram-positive bacteria. More specifically, the superabsorbent polymer may exhibit antimicrobial activity against one or more types of bacteria classified as gram-positive bacteria. Alternatively, the superabsorbent polymer may exhibit antimicrobial activity against one or more types of bacteria classified as gram-negative bacteria. Alternatively, the superabsorbent polymer may exhibit antimicrobial activity against one or more types of bacteria classified as gram-negative bacteria and one or more types of bacteria classified as gram-positive bacteria.

[0092] Herein, "exhibiting antibacterial activity against specific bacteria" means that the number of bacteria obtained by absorbing synthetic urine inoculated with the test bacteria into a superabsorbent resin for which the antibacterial activity is to be determined and then incubating is significantly reduced compared to the number of reference bacteria obtained by absorbing synthetic urine inoculated with the test bacteria into a superabsorbent resin containing no antibacterial substance. Specifically, it means that the antibacterial reduction rate (%) calculated by the following equation 1 according to the antibacterial activity test to be described later is 50% or more.

[0093] [Equation 1]

[0094]

[0095] In the above equation,

[0096] C 样品 is the concentration of microorganisms in the culture medium containing the superabsorbent polymer containing the antibacterial substance (Co), and

[0097] C 参照 is the concentration of microorganisms (Co) in the culture medium of the superabsorbent polymer of Comparative Example 1 which does not contain an antibacterial substance.

[0098] More preferably, “exhibiting antibacterial activity against specific bacteria” means that the antibacterial reduction rate (%) calculated by Equation 1 is 60% or greater, 70% or greater, 80% or greater, 90% or greater, 95% or greater, or 99% or greater.

[0099] Gram-positive bacteria is a general term for bacteria that are stained purple when stained by Gram staining. The cell wall of Gram-positive bacteria is composed of several layers of peptidoglycan. Therefore, even when Gram-positive bacteria are stained with basic dyes such as crystal violet and treated with ethanol, they also show purple without changing color. Bacteria that are classified as such Gram-positive bacteria include Enterococcus faecalis, Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecium, Lactobacillus lactis, etc.

[0100] In addition, gram-negative bacteria is a general term for the bacterium that is dyed red when dyed by Gram staining. Compared with gram-positive bacteria, gram-negative bacteria have the outer membrane that is made of lipopolysaccharide, lipoprotein and other complicated polymer substances instead of the cell wall with relatively small amount of peptidoglycan. Therefore, when gram-negative bacteria are treated with ethanol with basic dyes such as crystal violet, discoloration occurs, and when red dyes such as safranin are counterstained, redness is displayed. The bacterium that is classified as such gram-negative bacteria includes Proteus mirabilis, Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, Vibrio cholerae etc.

[0101] Gram-positive bacteria and Gram-negative bacteria may cause various diseases after contact, and may also cause secondary infections in critically ill patients with weakened immunity. Therefore, it is preferred to use one antibacterial agent to exhibit antibacterial activity against both Gram-positive bacteria and Gram-negative bacteria.

[0102] Preferably, the superabsorbent polymer can exhibit antibacterial activity against both Gram-negative bacteria and Gram-positive bacteria. Herein, the Gram-negative bacteria for which the superabsorbent polymer exhibits antibacterial activity may be Proteus mirabilis or Escherichia coli, and the Gram-positive bacteria may be Enterococcus faecalis, but the present disclosure is not limited thereto.

[0103] Specifically, the centrifuge retention capacity (CRC) of the superabsorbent polymer for saline (0.9 wt% sodium chloride aqueous solution) for 30 minutes measured according to EDANA WSP 241.3 may be 31 g / g to 40 g / g. When the centrifuge retention capacity (CRC) is less than 31 g / g, the liquid retention capacity deteriorates, making the superabsorbent polymer unsuitable for use in sanitary products. More specifically, the centrifuge retention capacity (CRC) of the superabsorbent polymer may be 31 g / g or more, 32 g / g or more, 33 g / g or more, 34 g / g or more, or 35 g / g or more, and 40 g / g or less, 39 g / g or less, 38 g / g or less, or 37 g / g or less.

[0104] Therefore, the above-mentioned super absorbent polymer including a polymerizable antimicrobial monomer in a predetermined amount in the polymer may exhibit excellent antimicrobial activity while having a centrifuge retention capacity (CRC) of 31 g / g to 40 g / g.

[0105] Method for preparing superabsorbent polymer

[0106] Meanwhile, the super absorbent polymer can be prepared by the following preparation method, which comprises the following steps:

[0107] preparing a monomer composition by mixing an acrylic acid-based monomer containing an acidic group, a polymerizable antibacterial monomer represented by the following Chemical Formula 1, a basic substance, an internal cross-linking agent, and a polymerization initiator (step 1);

[0108] forming a hydrogel polymer by thermally or photopolymerizing the monomer composition (step 2); and

[0109] The super absorbent polymer containing polymer is formed by drying, pulverizing and classifying the hydrogel polymer (step 3).

[0110] At this time, the polymerizable antibacterial monomer is used in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer, so that the polymerizable antibacterial monomer is contained in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer in the finally prepared super absorbent polymer.

[0111] First, to prepare a super absorbent polymer of one embodiment, step 1 of preparing a monomer composition by mixing an acrylic-based monomer containing an acidic group, a polymerizable antibacterial monomer represented by Chemical Formula 1, a basic substance, an internal crosslinking agent, and a polymerization initiator is performed.

[0112] For details about the acrylic acid-based monomer, the polymerizable antibacterial monomer, the alkaline substance and the internal crosslinking agent, refer to the above. In step 1, some of the acidic groups of the acrylic acid-based monomer and some of the carboxyl groups of the polymerizable antibacterial monomer are neutralized by mixing with the alkaline substance. Therefore, the monomer composition may include an acrylic acid-based monomer having an at least partially neutralized acidic group and a polymerizable antibacterial monomer having a carboxyl group (COOH) in Chemical Formula 1 that is at least partially neutralized.

[0113] At this time, as described above, the neutralization degree of the acrylic acid-based monomer and the polymerizable antibacterial monomer in the monomer composition can be independently 40mol% to 95mol%. For this reason, based on 1mol of acrylic acid-based monomer, the alkaline substance can be used in the monomer composition in an amount of about 0.4mol to about 0.95mol. In addition, the alkaline substance can be added to the monomer composition in the form of an aqueous solution dissolved in water.

[0114] In addition, based on 100 parts by weight of the acrylic acid-based monomer, the internal crosslinking agent may be included in the monomer composition in an amount of 0.01 to 1 parts by weight to crosslink the polymerized polymer. When the internal crosslinking agent is included in an amount less than 0.01 parts by weight, the improvement by crosslinking is not significant, and when the internal crosslinking agent is included in an amount greater than 1 part by weight, the absorbency of the superabsorbent polymer may be reduced. More specifically, based on 100 parts by weight of the acrylic acid-based monomer, the internal crosslinking agent may be included in an amount of 0.05 parts by weight or more, or 0.1 parts by weight or more, and 0.5 parts by weight or less, or 0.3 parts by weight or less.

[0115] In addition, polymerization initiator can be appropriately selected according to the polymerization method. In the case of thermal polymerization, thermal polymerization initiator is used, and in the case of photopolymerization, photopolymerization initiator is used. In addition, in the case of mixed polymerization method (method using both heat and light), thermal polymerization initiator and photopolymerization initiator can be used. However, even by photopolymerization method, a certain amount of heat is also generated by UV irradiation, and some heat is also generated as the polymerization reaction (exothermic reaction) is carried out. Therefore, the composition can additionally include thermal polymerization initiator.

[0116] As the photopolymerization initiator, any compound that can form radicals by light (eg, UV rays) may be used without limitation.

[0117] For example, the photopolymerization initiator can be one or more compounds selected from the following: benzoin ether, dialkyl acetophenone, hydroxyalkyl ketone, phenyl glyoxylate, benzyl dimethyl ketal, acyl phosphine, and α-amino ketone. In addition, specific examples of acyl phosphine include diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide, (2,4,6-trimethylbenzoyl) phenyl phosphite ethyl ester, etc. More different photopolymerization initiators are fully disclosed in "UV Coatings: Basics, Recent Developments and New Application (Elsevier, 2007)" written by Reinhold Schwalm, page 115, and the present disclosure is not limited thereto.

[0118] The photopolymerization initiator may be used in an amount of 0.001 to 1 parts by weight based on 100 parts by weight of the acrylic acid-based monomer. When the content of the photopolymerization initiator is less than 0.001 parts by weight, the polymerization rate may be slow, and when the content is greater than 1 part by weight, the molecular weight of the superabsorbent polymer may be low and the characteristics may be uneven. More specifically, the photopolymerization initiator may be used in an amount of 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.1 parts by weight or more and 0.5 parts by weight or less, or 0.3 parts by weight or less, based on 100 parts by weight of the acrylic acid-based monomer.

[0119] In the case where a thermal polymerization initiator is also included as a polymerization initiator, one or more initiators selected from the following can be used as the thermal polymerization initiator: a persulfate-based initiator, an azo-based initiator, hydrogen peroxide, and ascorbic acid. Specifically, sodium persulfate (Na 2 S 2 O 8 ), potassium persulfate (K 2 S 2 O 8 ), ammonium persulfate ((NH 4 ) 2 S 2 O 8) etc. as examples of persulfate-based initiators; and 2,2-azobis(2-amidinopropane) dihydrochloride, 2,2-azobis-(N,N-dimethylene)isobutyramidine dihydrochloride, 2-(carbamoyl azo)isobutyronitrile, 2,2-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 4,4-azobis-(4-cyanovaleric acid) etc. can be used as examples of azo-based initiators. More different thermal polymerization initiators are fully disclosed in 'Principle of Polymerization (Wiley, 1981)' written by Odian, page 203, and the present disclosure is not limited thereto.

[0120] The thermal polymerization initiator may be included in an amount of 0.001 to 1 part by weight based on 100 parts by weight of the acrylic acid-based monomer. When the thermal polymerization initiator is included in an amount of less than 0.001 parts by weight, additional thermal polymerization hardly occurs, and the effect of adding the thermal polymerization initiator may be low. When the thermal polymerization initiator is included in an amount greater than 1 part by weight, the molecular weight of the superabsorbent polymer may become low and the characteristics may be uneven. More specifically, the thermal polymerization initiator may be included in an amount of 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.1 parts by weight or more, and 0.5 parts by weight or less, or 0.3 parts by weight or less, based on 100 parts by weight of the acrylic acid-based monomer.

[0121] Furthermore, the monomer composition may further contain additives such as a surfactant, a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.

[0122] Furthermore, the monomer composition may be prepared in the form of a solution dissolved in a solvent.

[0123] At this point, any solvent that can dissolve the above components can be used without restriction. For example, the solvent can be a combination of at least one selected from the following: water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butylene glycol, propylene glycol, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl amyl ketone, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol ethyl ether, toluene, xylene, butyrolactone, carbitol, methyl cellosolve acetate and N, N-dimethylacetamide. The solvent can be included in the monomer composition with a residual amount other than the above components.

[0124] Next, step 2 of forming a hydrogel polymer by thermally or photopolymerizing the monomer composition is performed.

[0125] Herein, the thermal polymerization method and the photopolymerization method are not particularly limited as long as they are common methods capable of forming a hydrogel polymer by polymerizing a monomer composition.

[0126] For example, photopolymerization can be performed by irradiating ultraviolet rays with an intensity of 3 to 30 mW, or 10 to 20 mW at a temperature of 60 to 90° C., or 70 to 80° C. In the case of photopolymerization under the above conditions, a polymer having excellent polymerization efficiency can be formed.

[0127] In addition, the photopolymerization may be performed in a reactor equipped with a movable conveyor belt or in a stainless steel container having a certain size. However, the above-mentioned polymerization method is an example, and the present disclosure is not limited thereto.

[0128] In addition, when photopolymerization is carried out in a reactor equipped with a movable conveyor as described above, the hydrogel polymer obtained can generally be a sheet-like hydrogel polymer with a width of a belt. In this case, the thickness of the polymer sheet can be changed according to the concentration and injection speed of the monomer composition to be injected, and preferably the monomer composition is fed so that a sheet-like polymer with a thickness of about 0.5 cm to about 5 cm can be obtained. When the thickness of the sheet-like polymer becomes too thin due to the feeding of the monomer mixture, the production efficiency is low, which is undesirable. When the thickness of the sheet-like polymer is greater than 5 cm, due to the excessively thick thickness, the polymerization reaction cannot be carried out uniformly over the entire thickness.

[0129] The water content of the hydrogel polymer obtained in step 2 may be about 40% to about 80% by weight based on the total weight of the hydrogel polymer. Meanwhile, the "water content" in the present disclosure is the content of moisture in the total weight of the hydrogel polymer, and it means a value obtained by subtracting the weight of the dried polymer from the weight of the hydrogel polymer. Specifically, the water content is defined as a value calculated by the weight loss caused by the evaporation of water from the polymer during the process of increasing the temperature of the polymer by infrared heating for drying. At this time, the drying conditions for measuring the water content are as follows: the temperature is increased to about 180° C. and maintained at 180° C., and the total drying time is 20 minutes (including 5 minutes of the heating step).

[0130] Meanwhile, after the hydrogel polymer is prepared, a coarse pulverization process of pulverizing the prepared hydrogel polymer before the subsequent drying and pulverization processes may be optionally performed.

[0131] The coarse pulverization process is a process for improving the drying efficiency in the subsequent drying process and controlling the particle size of the super absorbent polymer powder to be prepared, and the pulverizer used is not particularly limited. Specifically, it may include at least one selected from the following: a vertical pulverizer, a turbine cutter, a turbine grinder, a rotary cuttermill, a cutter mill, a disc mill, a chip crusher, a chopper, a meat grinder, and a disc cutter, but it is not limited thereto.

[0132] During the coarse pulverization process, the hydrogel polymer may be pulverized to have a diameter of about 1 mm to 10 mm. Due to the high water content of the hydrogel polymer, it is technically difficult to coarsely pulverize the hydrogel polymer to have a diameter of less than 1 mm, and there may be a phenomenon in which the pulverized particles adhere to each other. At the same time, when the polymer is coarsely pulverized to have a diameter greater than 10 mm, the efficiency improvement effect in the subsequent drying step may not be significant.

[0133] Subsequently, step 3 of forming a super absorbent polymer containing polymer by drying, pulverizing and classifying the hydrogel polymer is performed.

[0134] The drying method is not particularly limited as long as it is generally used in the drying process of the hydrogel polymer. Specifically, the drying step can be performed by hot air supply, infrared radiation, microwave radiation, UV ray radiation, and the like.

[0135] Specifically, drying can be performed at about 150° C. to about 250° C. When the drying temperature is lower than about 150° C., the drying time may become too long, and the properties of the super absorbent polymer finally prepared may be reduced. When the drying temperature is higher than about 250° C., only the surface of the polymer is overdried, a large amount of fine powder may be generated in the subsequent pulverization process, and the properties of the super absorbent polymer finally prepared may be reduced. Therefore, drying may preferably be performed at a temperature of 150° C. or higher, or 160° C. or higher, and 200° C. or lower, or 180° C. or lower.

[0136] Meanwhile, considering process efficiency, the drying time may be about 20 minutes to about 90 minutes, but is not limited thereto.

[0137] The moisture content of the polymer after the drying step may be from about 5 wt % to about 10 wt %.

[0138] Meanwhile, a pulverizing process is performed after the drying step. The pulverizing process may be performed so that the particle diameter of the polymer powder, i.e., superabsorbent polymer particles, is about 150 μm to about 850 μm. In order to pulverize the polymer into such a diameter, a pin mill, a hammer mill, a spiral mill, a roller mill, a disc mill, or an inching mill may be used as a pulverizer, but the present disclosure is not limited thereto.

[0139] Furthermore, after the pulverization step, in order to control the characteristics of the super absorbent polymer powder to be finally commercialized, the pulverized polymer powder may be subjected to a classification process according to particle size.

[0140] The super absorbent polymer obtained as a result of the above process may be in the form of fine powder including a polymer in which an acrylic acid-based monomer and a polymerizable antibacterial monomer are crosslinked and polymerized using an internal crosslinking agent. Specifically, the super absorbent polymer may be in the form of fine powder having a particle size of 150 to 850 μm.

[0141] Subsequently, the method may further include a surface crosslinking step of heat-treating the superabsorbent polymer prepared in step 3 in the presence of a surface crosslinking agent. Through the above steps, a superabsorbent polymer further comprising a surface crosslinked layer formed on the polymer by further crosslinking the polymer using a surface crosslinking agent may be prepared. For details on the surface crosslinking agent, refer to the above.

[0142] Surface crosslinking is a step of increasing the crosslinking density near the surface of the superabsorbent polymer relative to the crosslinking density inside the particle. Typically, a surface crosslinking agent is applied to the surface of the polymer. Therefore, a surface crosslinking reaction occurs on the surface of the polymer, which improves the crosslinkability on the surface of the particle without substantially affecting the interior of the particle. Therefore, the surface crosslinked superabsorbent polymer has a higher degree of crosslinking at the surface than inside.

[0143] In addition, the surface crosslinking agent can be used in an amount of about 0.001 parts by weight to about 5 parts by weight based on 100 parts by weight of the superabsorbent polymer. For example, the surface crosslinking agent can be used in an amount of 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.05 parts by weight or more, and 5 parts by weight or less, 4 parts by weight or less, or 3 parts by weight or less based on 100 parts by weight of the superabsorbent polymer. When the surface crosslinking agent is used within the above range, a superabsorbent polymer having excellent absorption-related physical properties can be prepared.

[0144] In addition, the method of mixing the surface crosslinking agent with the super absorbent polymer is not particularly limited. For example, a method of adding the surface crosslinking agent and the super absorbent polymer to a reactor for mixing; a method of spraying the surface crosslinking agent onto the super absorbent polymer; or a method of mixing the super absorbent polymer and the surface crosslinking agent while continuously supplying them to a continuously operated mixer can be used.

[0145] Surface crosslinking can be carried out by heating the superabsorbent polymer together with the above-mentioned surface crosslinking agent at a temperature of about 80°C to about 220°C for about 15 minutes to about 100 minutes. When the crosslinking temperature is lower than 80°C, the surface crosslinking reaction may not fully occur, and when it exceeds 220°C, the surface crosslinking reaction may be excessively carried out. In addition, when the crosslinking time is too short (shorter than 15 minutes), the crosslinking reaction may not fully occur, and when the crosslinking time exceeds 100 minutes, the crosslinking density on the particle surface may become too high due to excessive surface crosslinking, which may cause deterioration of physical properties. More specifically, the surface crosslinking can be carried out by heating at a temperature of 120°C or higher, or 140°C or higher, and 200°C or lower, or 180°C or lower for 20 minutes or longer, or 40 minutes or longer, and 70 minutes or shorter, or 60 minutes or shorter.

[0146] The heating method for the surface cross-linking reaction is not particularly limited. A thermal medium can be provided thereto or a heat source can be directly provided thereto. At this time, the available thermal medium can be a heated fluid such as steam, hot air, hot oil, etc., but the present invention is not limited thereto. In addition, considering the method of the thermal medium, the heating rate and the target temperature of the heating, the temperature of the thermal medium provided thereto can be appropriately selected. Meanwhile, an electric heater or a gas heater can be used as the heat source directly provided, but the present disclosure is not limited thereto.

[0147] Meanwhile, a sanitary product comprising the superabsorbent polymer is also provided.

[0148] Hereinafter, the present invention will be described in more detail with reference to Examples. However, these Examples are for illustrative purposes only, and the present invention is not intended to be limited by these Examples.

[0149] Preparation Example A: Preparation of polymerizable antibacterial monomer 1-1 (3-(acryloyloxy)benzoic acid)

[0150]

[0151] A solution of 26.67 g of 3-hydroxybenzoic acid and 15.63 g of NaOH dissolved in 100 mL of water was placed in a 250 ml round bottom flask, and 50 mL of 1,4-dihydrobenzoic acid was added thereto. A solution of 19.39 g of acryloyl chloride in oxane was prepared. At this time, the addition was slowly performed dropwise at 0° C. using a dropping funnel. 1,4-dichloroacetyl chloride in which acryloyl chloride was dissolved was added. When the addition of the oxane solution was completed, the reaction was carried out under stirring at room temperature for 4 hours. After the reaction, hydrochloric acid was added until the pH of the reaction solution reached 2 to 3 to obtain a liquid product. The obtained liquid product was dissolved in a dichloromethane (MC) solvent, and then water was added thereto for extraction. Thereafter, it was recrystallized with water to obtain the title compound polymerizable antibacterial monomer 1-1 in the form of a solid. At the same time, the obtained polymerizable antibacterial monomer 1-1 1 H NMR spectrum is shown in Figure 1 middle.

[0152] MS[M+H] + =193

[0153] 1 H NMR (500 MHz, DMSO-d 6 ,δ[ppm])"6.1(dd,1H,CH 2 =CH),6.3(dd,1H,CH 2 =CH),6.5(dd,1H,CH 2 =CH),7.4(d,1H,Ar-H),7.5(d,1H,Ar-H),7.6(d,1H,Ar-H),7.8(d,1H,Ar-H),13.1(s,1H,COOH).

[0154] Example - Preparation of Superabsorbent Polymer Compositions

[0155] Example 1

[0156] (Step 1) In a 3 L glass container equipped with a stirrer, a nitrogen inlet and a thermometer, 100 g of acrylic acid, 0.25 g of polyethylene glycol diacrylate (Mn=575) as an internal crosslinking agent, 0.00625 g of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide as a photoinitiator, 0.125 g of sodium persulfate (SPS) as a thermal initiator, 100 g of a 40% sodium hydroxide solution and 0.5 g of the polymerizable antibacterial monomer 1-1 prepared in Preparation Example A were added while continuously adding nitrogen to prepare a monomer composition. At this time, the neutralization degree of acrylic acid and the polymerizable antibacterial monomer 1-1 was 70 mol%.

[0157] (Step 2) Then, the monomer composition was added to a 250 mm wide and 250 mm long mm And the height is 30 mm The samples were placed in a stainless steel container and irradiated with ultraviolet light for 60 seconds in a UV chamber at 80°C (irradiation dose: 10 mV / cm2 ), and then aged for 2 minutes to prepare a sheet-type hydrogel polymer.

[0158] (Step 3) The prepared hydrogel polymer was cut into a size of 3 cm*3 cm, and then put into a meat grinder for pulverization to obtain hydrogel particle crumbs with a size of 1 mm to 10 mm. The obtained crumbs were spread on a stainless steel wire mesh with a hole size of 600 μm to a thickness of about 30 mm, and dried in a hot air oven at 120°C for 11 hours. The dried polymer thus obtained was pulverized using a pulverizer and classified using an ASTM standard mesh to obtain a base resin with a particle size of 150 μm to 850 μm, which was used as a superabsorbent polymer.

[0159] Example 2

[0160] A super absorbent polymer was prepared in the same manner as in Example 1, except that 1.0 g of the polymerizable antibacterial monomer 1-1 prepared in Preparation Example A was used in Example 1.

[0161] Example 3

[0162] A super absorbent polymer was prepared in the same manner as in Example 1, except that 1.5 g of the polymerizable antibacterial monomer 1-1 prepared in Preparation Example A was used in Example 1.

[0163] Example 4

[0164] A super absorbent polymer was prepared in the same manner as in Example 1, except that 2.0 g of the polymerizable antibacterial monomer 1-1 prepared in Preparation Example A was used in Example 1.

[0165] Comparative Example 1

[0166] A super absorbent polymer was prepared in the same manner as in Example 1, except that the polymerizable antibacterial monomer 1-1 was not used in Example 1.

[0167] Comparative Example 2

[0168] A super absorbent polymer was prepared in the same manner as in Example 1, except that 0.1 g of the polymerizable antibacterial monomer 1-1 was used in Example 1.

[0169] Comparative Example 3

[0170] A super absorbent polymer was prepared in the same manner as in Example 1, except that 100 g of the polymerizable antibacterial monomer 1-1 was used in Example 1.

[0171] Comparative Example 4

[0172] A super absorbent polymer was prepared in the same manner as in Example 1, except that 30 g of the polymerizable antibacterial monomer 1-1 was used in Example 1.

[0173] Experimental Example 1

[0174] The physical properties of the super absorbent polymers prepared in Examples and Comparative Examples were evaluated in the following manner, and the results are shown in Table 4 below.

[0175] Unless otherwise indicated, all steps were performed in a constant temperature and humidity chamber (23±1° C., relative humidity 50±10%), and physiological saline or saline means 0.9 wt % sodium chloride (NaCl) aqueous solution.

[0176] (1) Evaluation of antibacterial activity against Escherichia coli

[0177] After 2g of the superabsorbent polymer prepared in one of the embodiments and comparative examples was placed in a 250 cell culture bottle, 50ml of synthetic urine inoculated with 3000±300CFU / ml of the tested microorganism Escherichia coli (ATCC 25922) was injected. Then, the superabsorbent polymer was mixed for about 1 minute to fully absorb the synthetic urine solution, and the polymer fully absorbed with the solution was in the form of a gel, which was incubated in an incubator (manufactured by JEIO TECH) maintained at 35°C for 12 hours. 150mL of 0.9 wt% NaCl solution was added to the incubated sample, shaken for about 1 minute, and the diluted solution was spread on an agar medium plate. Afterwards, serial dilutions were performed to achieve colony counts, and 0.9 wt% NaCl solution was used in the process. For the antibacterial performance, after calculating the initial concentration of microorganisms (Co, CFU / mL) considering the dilution concentration, the antibacterial reduction rate (%) of Escherichia coli (ATCC 25922) was calculated according to the following Equation 1, and the results are shown in Table 4 below.

[0178] [Equation 1]

[0179]

[0180] In the above equation,

[0181] C 样品 is the concentration of microorganisms in the culture medium containing the superabsorbent polymer containing the antibacterial substance (Co), and

[0182] C 参照 is the concentration of microorganisms (Co) in the culture medium of the superabsorbent polymer of Comparative Example 1 which does not contain an antibacterial substance.

[0183] At this time, synthetic urine for evaluation of antibacterial activity was prepared as follows.

[0184] First, a stock solution was prepared by placing the reagents listed in Table 1 in a 1000 mL flask at the following weights, adding water to 1000 mL, and then mixing. Then, a cationic solution was prepared by placing the reagents listed in Table 2 in a 100 mL flask at the following weights, adding water to 20 mL, and then mixing. Thereafter, a urea / glucose solution was prepared by placing the reagents listed in Table 3 in a 100 mL flask at the following weights, adding water to 100 mL, and then mixing.

[0185] Subsequently, the prepared stock solution and cationic solution were sterilized at 120°C for 15 minutes using an autoclave and fully cooled to room temperature.Then, the prepared urea / glucose solution was treated with a 0.22 μm syringe filter (hydrophilic, manufactured by Sartorius stedim) to remove impurities.

[0186] Thereafter, 940 mL of the stock solution, 10 mL of the cation solution and 50 mL of the urea / glucose solution were fully mixed to prepare synthetic urine. The prepared synthetic urine was generally stored in a refrigerator and could be used for 2 weeks, and synthetic urine after 2 weeks was not used for experiments.

[0187] [Table 1]

[0188]

[0189] [Table 2]

[0190]

[0191]

[0192] [Table 3]

[0193]

[0194] (2) Centrifugal retention capacity (CRC)

[0195] The centrifuge retention capacity according to the absorbency under no-load conditions of the superabsorbent polymer prepared in one of the Examples and Comparative Examples was measured according to EDANA (European Disposables and Nonwovens Association, EDANA) WSP 241.3.

[0196] Specifically, when W 0 After the superabsorbent polymer (g, about 0.2 g) was uniformly inserted into the nonwoven fabric envelope and sealed, it was immersed in physiological saline (0.9 wt % sodium chloride aqueous solution) at room temperature. After 30 minutes, the envelope was centrifuged at 250 G for 3 minutes to drain water, and the weight of the envelope was measured. 2 (g). In addition, after the same operation was performed without using the polymer, the weight W of the encapsulated material was measured.1 Then, CRC (g / g) was calculated according to the following equation using the obtained weight value, and the results are shown in Table 4 below.

[0197] [Equation 2]

[0198] CRC(g / g)={[W 2 (g)-W 1 (g)] / W 0 (g)}-1

[0199] In equation 2,

[0200] W 0 (g) is the initial weight of the superabsorbent polymer (g),

[0201] W 1 (g) is the weight of the encapsulate not containing the superabsorbent polymer measured after immersing the encapsulate in physiological saline for 30 minutes and dehydrating it by using a centrifuge at 250 G for 3 minutes, and

[0202] W 2 (g) is the weight of the superabsorbent polymer-containing package measured after immersing the superabsorbent polymer in physiological saline at room temperature for 30 minutes and dehydrating it by using a centrifuge at 250 G for 3 minutes.

[0203] [Table 4]

[0204]

[0205] 1) Based on 100 parts by weight of acrylic acid, in parts by weight

[0206] Referring to Table 4, the superabsorbent polymer of the example has a centrifuge retention capacity (CRC) comparable to that of the superabsorbent polymer of Comparative Example 1 not containing a polymerizable antimicrobial monomer, and exhibits excellent antibacterial activity against Escherichia coli, which is one of Gram-negative bacteria.

[0207] Meanwhile, it was determined that the superabsorbent polymer of Comparative Example 2, in which the polymerizable antimicrobial monomer was contained in the polymer in an amount of less than 0.2 parts by weight based on 100 parts by weight of the acrylic acid monomer, did not exhibit antimicrobial activity against Escherichia coli. It was also determined that the superabsorbent polymer of Comparative Example 3, in which the polymerizable antimicrobial monomer was contained in the polymer in an amount of more than 20 parts by weight based on 100 parts by weight of the acrylic acid monomer, had a significantly reduced centrifuge retention capacity (CRC) compared to the superabsorbent polymer of Comparative Example 1.

[0208] Therefore, it was determined that the superabsorbent polymer of the examples containing a polymerizable antimicrobial monomer in a predetermined amount in the polymer exhibited excellent antimicrobial activity while having a centrifuge retention capacity (CRC) of 31 to 40 g / g for saline (0.9 wt % sodium chloride aqueous solution) for 30 minutes measured according to EDANA WSP 241.3.

[0209] The present application further includes the following embodiments:

[0210] Embodiment 1. A superabsorbent polymer comprising an acrylic acid-based monomer, a polymerizable antibacterial monomer represented by the following Chemical Formula 1, and a polymer of an internal crosslinking agent, wherein the acrylic acid-based monomer contains an acidic group, wherein at least a portion of the acidic group is neutralized,

[0211] Wherein the polymerizable antibacterial monomer is contained in the polymer in an amount of 0.2 parts by weight to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer:

[0212] [Chemical formula 1]

[0213]

[0214] In the chemical formula 1,

[0215] R 1 To R 3 are each independently hydrogen or methyl, and

[0216] A is a substituted or unsubstituted C6 to C60 aromatic ring.

[0217] Embodiment 2. The superabsorbent polymer according to embodiment 1,

[0218] The polymerizable antibacterial monomer is included in the polymer in an amount of 0.5 parts by weight to 2 parts by weight based on 100 parts by weight of the acrylic acid-based monomer.

[0219] Embodiment 3. The superabsorbent polymer according to embodiment 1,

[0220] Wherein in the chemical formula 1,

[0221] A is a benzene ring which is unsubstituted or substituted with at least one substituent selected from the group consisting of a C1 to C4 alkyl group, a hydroxyl group and a carboxyl group.

[0222] Embodiment 4. The superabsorbent polymer according to embodiment 1,

[0223] The polymerizable antibacterial monomer is any one selected from the following:

[0224]

[0225] Embodiment 5. The superabsorbent polymer according to embodiment 1,

[0226] Also included is a surface cross-linked layer formed on the polymer by further cross-linking the polymer using a surface cross-linking agent.

[0227] Embodiment 6. The superabsorbent polymer according to embodiment 1,

[0228] The superabsorbent polymer exhibits antibacterial activity against at least one of Gram-negative bacteria and Gram-positive bacteria.

[0229] Embodiment 7. The superabsorbent polymer according to embodiment 6,

[0230] wherein the Gram-negative bacteria is Proteus mirabilis or Escherichia coli, and

[0231] The Gram-positive bacteria is Enterococcus faecalis.

[0232] Embodiment 8. The superabsorbent polymer according to embodiment 1,

[0233] The superabsorbent polymer has a centrifuge retention capacity (CRC) of 31 g / g to 40 g / g for saline (0.9 wt % sodium chloride aqueous solution) for 30 minutes measured according to EDANA WSP 241.3.

[0234] Embodiment 9. A method for preparing a superabsorbent polymer, comprising the following steps:

[0235] preparing a monomer composition by mixing an acrylic acid-based monomer containing an acidic group, a polymerizable antibacterial monomer represented by the following Chemical Formula 1, a basic substance, an internal cross-linking agent, and a polymerization initiator;

[0236] forming a hydrogel polymer by thermally polymerizing or photopolymerizing the monomer composition; and

[0237] forming a super absorbent polymer comprising a polymer by drying, pulverizing and classifying the hydrogel polymer,

[0238] Wherein the polymerizable antibacterial monomer is used in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer:

[0239] [Chemical formula 1]

[0240]

[0241] In the chemical formula 1,

[0242] R1 To R 3 are each independently hydrogen or methyl, and

[0243] A is a substituted or unsubstituted C6 to C60 aromatic ring.

[0244] Embodiment 10. The method for preparing a superabsorbent polymer according to embodiment 9,

[0245] The neutralization degrees of the acrylic acid-based monomer and the polymerizable antibacterial monomer in the monomer composition are each independently 40 mol % to 95 mol %.

[0246] Embodiment 11. A method for preparing a superabsorbent polymer according to Embodiment 9,

[0247] The method further comprises a surface crosslinking step of heat-treating the superabsorbent polymer in the presence of a surface crosslinking agent.

[0248] Embodiment 12. A hygiene product comprising the superabsorbent polymer according to any one of Embodiments 1 to 8.

Claims

1. A superabsorbent polymer comprising an acrylic acid-based monomer, a polymerizable antibacterial monomer represented by the following Chemical Formula 1, and a polymer of an internal crosslinking agent, wherein the acrylic acid-based monomer contains an acidic group, wherein at least a portion of the acidic group is neutralized, Wherein the polymerizable antibacterial monomer is contained in the polymer in an amount of 0.2 parts by weight to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer: [Chemical formula 1] In the chemical formula 1, R1 to R3 are each independently hydrogen or methyl, and A is a substituted or unsubstituted C6 to C60 aromatic ring.

2. The superabsorbent polymer according to claim 1, The polymerizable antibacterial monomer is included in the polymer in an amount of 0.5 parts by weight to 2 parts by weight based on 100 parts by weight of the acrylic acid-based monomer.

3. The superabsorbent polymer according to claim 1, Wherein in the chemical formula 1, A is a benzene ring which is unsubstituted or substituted with at least one substituent selected from the group consisting of a C1 to C4 alkyl group, a hydroxyl group and a carboxyl group.

4. The superabsorbent polymer according to claim 1, The polymerizable antibacterial monomer is any one selected from the following:

5. The superabsorbent polymer according to claim 1, Also included is a surface cross-linked layer formed on the polymer by further cross-linking the polymer using a surface cross-linking agent.

6. The superabsorbent polymer according to claim 1, The superabsorbent polymer exhibits antibacterial activity against at least one of Gram-negative bacteria and Gram-positive bacteria.

7. The superabsorbent polymer according to claim 6, wherein the Gram-negative bacteria is Proteus mirabilis or Escherichia coli, and The Gram-positive bacteria is Enterococcus faecalis.

8. The superabsorbent polymer according to claim 1, The superabsorbent polymer has a centrifuge retention capacity for a 0.9 wt % sodium chloride aqueous solution for 30 minutes measured according to EDANA WSP 241.3 of 31 g / g to 40 g / g.

9. A method for preparing a superabsorbent polymer, comprising the following steps: preparing a monomer composition by mixing an acrylic acid-based monomer containing an acidic group, a polymerizable antibacterial monomer represented by the following Chemical Formula 1, a basic substance, an internal cross-linking agent, and a polymerization initiator; forming a hydrogel polymer by thermally polymerizing or photopolymerizing the monomer composition; and forming a super absorbent polymer comprising a polymer by drying, pulverizing and classifying the hydrogel polymer, Wherein the polymerizable antibacterial monomer is used in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of the acrylic acid-based monomer: [Chemical formula 1] In the chemical formula 1, R1 to R3 are each independently hydrogen or methyl, and A is a substituted or unsubstituted C6 to C60 aromatic ring.

10. The method for preparing a superabsorbent polymer according to claim 9, The neutralization degrees of the acrylic acid-based monomer and the polymerizable antibacterial monomer in the monomer composition are each independently 40 mol % to 95 mol %.

11. The method for preparing a superabsorbent polymer according to claim 9, The method further comprises a surface crosslinking step of heat-treating the superabsorbent polymer in the presence of a surface crosslinking agent.

12. A hygiene product comprising the superabsorbent polymer according to any one of claims 1 to 8.

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